Abrasive tool



May 3, 1966 E. A. zuzL-:Lo 3,248,824

ABRASIVE TOOL Original Filed Nov. 22, 1961 INVENTOR WW/W0 ,4. Z UZHO United States Patent 3,248,824 ABRASIVE TOOL Edward A. Zuzelo, 652 Broad Acres Road, Nal-berth, Pa. Continuation of application Ser. No. 154,157, Nov. 22, 1961. This application Mar. 11, 1964, Ser. No. 351,127 12 Claims. (Cl. 51-209) The present application is a continuation of my copending application, Serial No. 154,157 filed November 22, 1961 and now abandoned, for Abrasive Tool.

This invention relates to abrasive tools, such as are useful for abrading a work surface to grind or polish it, and concerns also means and methods for their prod-uction.

Disc-shaped abrasive wheels are well known tools for grinding or polishing metal, stone, and other materials. Such tools conventionally are used by presenting either the peripheral edge or one face of the rotating Wheel to the Work. Also known are dis-hed or offset abrasive wheels, which have a raised or depressed hub or center portion; they present only a relatively narrow abrading surface regardless of their orientation to the work. Except when most skillfully used an abrasive wheel is conducive to arcuate scoring of the work surface, because of uninterrupted contact of the work surface with the Wheel rim, and this difliculty often is aggravated by excessive abrasion caused by fragments worn from the Work or the wheel and trapped therebetween. Some abrasive wheels are reinforced by a covering or embedded layer of fabric, usually of glass, to prevent disintegration at high speeds.

A primary object of the present invention is provision of a rotary abrasive tool with an annular working surface of substantial Width.

An object is formation of a dished or offset rotary abrasive tool non-conducive to scoring of the work surface being abraded thereby.

Another object is production of a rotary abrasive -tool adapted to expose the surface of the Work while it is being abraded with the tool.

Other objects of this invention, ltogether with means and methods for attaining the various objects will be apparent from the following description and the accompanying diagrams.

FIG. 1 is a plan of a rst embodiment of rotary abrasive tool according to the present invention;

FIG. 2 is a side elevation, partly in section, of the abrasive tool of FIG. l;

FIG. 3 is an enlarged sectional elevation of a portion of a wall construction useful in such an abrasive tool;

FIG. 4 is a plan of another embodiment of abrasive tool according to this invention;

FIG. 5 yis a sectional elevation of another wall construction useful in abrasive tools of this invention;

FIG. 6 is a block diagram of the production of abrasive tools of this invention; and

FIG. 7 is a schematic representation of a continuous method for processing component materials into rotafy abrasive tools according to this invention.

In general, the objects of the present invention are accomplished by providing a hollow pyramidal abrasive tool open at its base. The invention comprehends particularly such a tool truncated to provide a hub for a drive shaft, also preferably bored axially to receive such a shaft, and with its lateral faces containing abrasive material.

As used herein the ter-m pyramidal signifies generally a regular poly-hedral configuration having a polygonal base and generally triangular lateral faces. These lateral faces, which preferably are both regular and identical, are actually trapezoidal in the .preferred pyramidal config-uration, which is truncated or frustopyramidal. The polygon may be four-sided, six-sided, etc., and in accordance with the above preference for regular faces, is preferably equilateral (e.g., square, rather than oblong, in the foursided configuration). Of course, in the physical structure of the abrasive tools of this invention the lateral faces' have a finite wall thickness, as does the end face (i.e., the hub) provided by the truncation, while the polygonal base is defined by the peripheral edge of the wall comprising the lateral faces and is otherwise open to the interior.

FIG. 1 shows in plan view rotary abrasive tool 10, which is exemplary of the present invention. It has square hub 18 with central bore 19 through it. Trapezoidal lateral faces 11, 12, 13, and 14 surround the hub and terminate in a peripheral edge having a square outline. FIG. 2 shows the abrasive .tool of FIG. l from the side, with lateral face 12 partly cut away to reveal a portion of the hollow interior and (in section) a portion of the wall of lateral face 11.

FIG. 3 shows, in greater sectional detail than in FIG. 2, a wall construction suitable for the abrasive tools of this invention. Here outer and inner facing layers 27 and 29 sandwich central layer 2,8 of t-he wall.

The composition of the facing layers of the Wall may be p-aper, textile fabric (often glass), or wire fabric or mesh, for example. Paper may function during manufacture to support or confine the abrasive material, as may be important in certain stages of manufacture, While the other mentioned compositions serve also to reinforce the structure of the manufactured tool itself. With well bonded central layers either (or both) of the facing layers may become less important or even unnecessary and accordingly may be omitted.

The central layer of the wall, which contains the abrasive proper, usually is composed of rubber or a thermosetting resin, such as phenol-formaldehyde or ureaformaldehyde, but may be other polymerizable or similarly hardenable material capable of bonding the finely divided abrasive particles together and adhering to the facing layers, which normally become embedded therein or impregnated therewith. The abrasive itself may be silicon carbide, aluminum oxide, or other sufficiently hard material. It is customary to mix the resin, in more or less granular form, with the smaller abrasive particles in the presence of a liquid, which may also be a softening agent or solvent for the resin material, adapted to wet both components so that the resin granules become coated with the abrasive particles. Subsequent heating, usually with application of pressure, bonds the componentsv together.

FIG. 4 shows in plan additional frustopyramidal abrasive tool 40 of this invention. This rotary tool is hexagonal in outline, instead of square, as was the first illustrated embodiment. It has hexagonal hub 48, with bore 49 through it, and trapezoidal lateral faces 41, 42, 43, 44, 45, and 46. In all other respects, including Wall composition, tools 10 and 40 are or may be alike.

FIG. 5 shows another Wall construction suitable for abrasive tools, constructed according to the present invention. Here, the tool wall has outer and inner facing layers 35 and 39 on its opposite sides and has intermediate reinforcing layer 37. Abrasive layers 36 and 38 of the wall are flanked on Ione side by the intermediate layer 37 and on the other side by one of the facing layers. Central reinforcing layer 37 preferably is made of open-mesh fabric, and either or both of the facing layers may be similarly comprised or may be of paper, for example, similarly to facing layers 27 and 29 of the Wall embodiment of FIG. 3.

Operation of the abrasive tools of this invention is readily understood. The bore of the hub receives a drive shaft D (not shown), such as the shaft of an electric motor, and is secured thereto. Rotation of the drive shaft rotates the tool. The operator holds the motor housing or some nonrotating support for the shaft. The tool will grind or polish a strip or annular ring of the Work when placed flat against it, i.e., with the base of the tool in contact with the Work. The portion of the work surface being abraded will be visible to the operator as the tool rotates, the tool acting, in effect, as a shutter with a repetition frequency equal to the number of sides to the polygonal base times the rotational speed (rpm.) of the shaft. The working surf-ace of the tool will be the polygonal base edge thereof. Although that ribbon-like edge or marginal portion of the tool when new is conveniently substantially perpendicular to the adjacent sloping faces of the tool, it soon will wear parallel to the work surface, which itself is presumably parallel to the tool hub. The facing and any intermediate fabric or paper layer or layers, being softer than the abrasive material itself, will wear off accordingly.

Production lof the abr-asive tools of this invention may be accomplished most simply and economically by a Icontinuous process. FIG. 6 is a block diagram lof such a process, comprising steps denoted as laminating, blanking, and forming. These steps may be conducted sequentially, as indicated by the arrows on the solid interconnecting lines, or the order of the last two steps may be reversed, as indicated by the arrows on the broken lines. The second and third steps may even be performed sufficiently closely together to be considered as simultaneous.

Laminating denotes the formation of one or more layers of abrasive material and -at least one facing or intermediate layer, as suggested above, into sheet configuration. Blanking is the step of subdividing the sheet into separate pieces or blanks, each on its way to becoming a finished article. Forming is the shaping of the flat laminate or pieces thereof, depending upon the order of the steps, by dies or the like into the desired pyramidal configuration. Bore formation may be accomplished in either the blanking or forming step or in a combined tblanking and forming step, as will be apparent,

FIG. 7, which represents schematically the process indicated by solid lines in FIG. 6, illustrates the formation of an abrasive tool of this invention having a five-layered wall corresponding to that shown in FIG. 5. Bottom facing layer 59 is fed in about roller 61 and passes under hopper 71, which contains material 72 and dispenses the material as layer 58 on the bottom facing layer. The dispensed material comprises chiefly resin particles (represented by circles) and finer abrasive particles (represented by dots). Intermediate reinforcing layer 57 is fed in about roller 62 and passes under hopper 73, which also contains a supply of material 72. This second hopper dispenses the material in layer 56 on the intermediate layer, which directly overlies previously dispensed layer 58. As

is customary in the dispensing art, each hopper is furnished 4 with appropriate mechanism (not shown) to ensure even deposition of the dispensed material in a layer -of desired thickness. Roller 63 underlies roller 62 and the intervening layers. Top facing layer 57 is fed in about roller 64 t-o overlie layer 56, thereby providing the five-layered configuration. Roller 65 underlies roller 64 and these intervening five layers.

The resultant laminate passes between additional pairs of rollers 66, 67 and 68, 69, which are successively more closely spaced so as t-o consolidate the structure. Reciprocating knife 71 cuts the laminate into successive individual pieces 70 (one shown), which then are forwarded individually by pair of rollers 72, 73 between pair of mating dies 75, 76 (shown in section). The dies close to form the piece into the desired frustopyramidal shape .and to cut the bore in the hub. Freed from the dies, resultant tools 80 (one shown) are removed by conveyor belt 78, which has drive roller 77, to an inspection or packaging location.' One or both of the dies may be heated by outside means (represented by lamps 79 in the vicinity of the dies) to assist in bonding and rigidifying the structure. Other modifications may be made Without departing from the inventive concept. To interchange or combine certain of these operations, in conformity with an alternative order of processing, as suggested above, is within the ability of a person having ordinary skill in the art, so only the single schematic lof FIG. 7 is given here.

Although only a single die set is shown, it will be understood that a multiplicity of sets can 4be employed and that a plurality of such die parts may be fastened together or supported side by side or lengthwise (or both) so as to form a corresponding number of blanks simultaneously from a sheet of substantial size. Although the illustrated dies are constructed to make square-edged tools as shown in FIGS. l and 2, it will be apparent that only ordinary principles of design need be applied to make six-sided tools like those in FIG. 4, or other configurations according to this invention. The peripheral or base edges of the tools may be fully formed by the dies or may be trimmed or ground, as will be apparent, in a separate finishing step if necessary to ensure the desired degree of regularity. The edges usually will be squared off substantially perpendicular to the hub or to the lateral faces, at least over part of the peripheral margin. The hub itself need not be bored for a drive shaft but may be fitted with a boss or shoulder to be gripped in a chuck, or with other equivalent drive means. The hub need not be similar in outline to the base but may be circular, for example.

Advantages inherent in the use of these dished abrasive tools have been pointed out above. Their use also leads to improved workmanship and lower working costs than obtained with abrasive wheels or other conventional grinding or Ipolished tools. The polygonal outline of the tools of this invention eliminates the manufacturing waste attributed to the circular outline of abrasive wheels. Further benefits of this invention will become apparent and accrue to those persons undertaking to practice it.

The claimed invention:

1. Dished rotary tool comprising abrasive material and having a hub defining an axis about which it is adapted to be rotated, a side wall made up of generally ytriangular faces extending from the hub to enclose a pyramidal space with an open base and provide the tool with a polygonal outline lwhen viewed along the axis, the tool being adapted, when rotated with the entire base in contact with a work surface to be abraded, to abrade an annular ring on the work surface and to expose essentially all the abraded ringlike portion lof the work surface to view during tool rotation.

2. Dished rotary tool comprising abrasive material and having a wall polygonal in outline as viewed along the axis of rotation and tapering to an adjoining offset hub, the wall having identical faces generally triangular in outline thickness of the wall faces being substantially constant throughout, the base defined by the furthest extent of the wall from the hub in an axial direction through the hub being planar and open to the interior, the interior .being open within the surrounding wall and being greater in least extent transverse to the axis than the thickness of the wall.

3. Dished rotary tool comprising abrasive material and having a thin-walled ribbon-like open polygonal base, an adjoining offset hub, and an interconnecting thin wall similarly polygonal in outline, as viewed along the axis of rotation and diminishing in size toward the hub, the wall outline being such that the loci of intersection thereof with a series of intersecting planes oriented parallel to the base constitute a selies of polygons differing from one another only in size, the tool being adapted, when rotated about the hub axis with the entire base in contact with an article to be abraded, to abrade an annular ring thereon and to expose to view during rotation a major portion of the abraded annular ring.

4. Resin-bonded rotary abrasive tool having a generally liat hub, a ribbon-like peripheral base surface having a polygonal conguration in outline as viewed along the axis of rotation, and an intermediate portion similarly polygonal in outline open throughout the interior thereof and joining the hub and the ribbon-like base surface; the intermediate portion having a number of identical faces equal to the number of sides of the polygonal outline, each face having the form of a trapezoidal lresidue left by truncation of an isosceles triangle; the hub, the ribbon-like surface, and the intermediate portion having a substantially uniform thickness and comprising a layer of abrasive material and a contiguous layer of reinforcing fabric.

5. Dished rotary tool comprising abrasive material and having a hub portion, an open polygonal peripheral abrasive base edge portion having from four to six sides and lying in a plane offset from the hub portion, and an intermediate portion open throughout the interior thereof and adjoining both the hub and peripheral base edge portions, the intermediate portion diminishing in size from the peripheral edge portion to the hub While retaining at successive loci of intersection with planes parallel to the base edge portion a polygonal configuration similar to that of the peripheral edge portion.

6. Rotary tool comprising abrasive material and having a hub, lfour inclined walls extending from the hub to an open base, the walls being identical, generally triangular in outline, with their apexes joined at the hub and the side edges of each two adjacent |walls joined at right angles to one another from the hub to the base, the interior of the tool being hollow from the hub to the base.

7. The tool of claim 1 in which the polygonal outline is tetragonal.

8. The tool of claim A1 in which the polygonal outline is pentagonal.

9. The tool of claim 1 in which the polygonal outline is hexagonal.

10. Dished rotary tool comprising abrasive material, open at its base and characterized by an essentially uniform wall thickness throughout, the wall outline being such that the loci of intersection thereof with a series of intersecting planes oriented parallel to the base and located at increasing distances from the base constitute a series of squares of decreasing size.

11. Dished rotary tool comprising abrasive material, having an open polygonal base and at most six sides, characterized -by an essentially uniform |Wall thickness throughout, the Wall outline being such that the loci of intersection thereof with a series of intersecting planes oriented parallel to the base and located at increasing distances from the base constitute a series of similar polygons of decreasing size.

12. Dished rotary tool comprising abrasive material, having an open, regular polygonal base, characterized by an essentially uniform wall thickness throughout, the Wall outline being such that the loci of intersection thereof with a series of intersecting planes oriented parallel to the base and located at increasing distances from the base constitute a series of similar polygons of decreasing size.

References Cited by the Examiner UNITED STATES PATENTS 881,621 3/ 1908 Rowland et al 51-209 2,746,216 5/ 1956 Hollingsworth 51-394 2,997,820 8/ 1961 Skoog 51-206 X ROBERT C. RIORDON, Primary Examiner.

LESTER M. SWINGLE, Examiner.

L. S. SELMAN, Assistant Examiner. 

12. DISHED ROTARY TOOL COMPRISING ABRASIVE MATERIAL, HAVING AN OPEN, REGULAR POLYGONAL BASE, CHARACTERIZED BY AN ESSENTIALLY UNIFORM WALL THICKNESS THROUGHOUT, THE WALL OUTLINE BEING SUCH THAT THE LOCI OF INTERSECTION THEREOF WITH A SERIES OF INTERSECTING PLANES ORIENTED PARALLEL TO THE BASE AND LOCATED AT INCREASING DISTANCES FROM THE BASE CONSTITUTE A SERIES OF SIMILAR POLYGONS OF DECREASING SIZE. 